What is Alzheimer's Disease?
Alzheimer's disease is the most common form of dementia, a serious brain disorder that impacts daily living through memory loss and cognitive changes.
Although not all memory loss indicates Alzheimer's disease, one in ten people over 65 years of age, and over half of those over 85 have Alzheimer's disease. Currently, 26 million people worldwide have this dementia, and over 15 million Americans will be affected by the year 2050.
Symptoms of Alzheimer's disease usually develop slowly and gradually worsen over time, progressing from mild forgetfulness to widespread brain impairment. Chemical and structural changes in the brain slowly destroy the ability to create, remember, learn, reason, and relate to others. As critical cells die, drastic personality loss occurs and body systems fail.
There are three major hallmarks in the brain that are associated with the disease processes of the AD.
1. Amyloid Plaques:
which are made up of fragments of a protein called beta-amyloid peptide mixed with a collection of additional proteins, remnants of neurons, and bits and pieces of other nerve cells.
2. Neurofibrillary Tangles (NFTs):
found inside neurons, are abnormal collections of a protein called tau. Normal tau is required for healthy neurons. However, in AD, tau clumps together. As a result, neurons fail to function normally and eventually die. Loss of connections between neurons responsible for memory and learning.
Neurons can't survive when they lose their connections to other neurons. As neurons die throughout the brain, the affected regions begin to atrophy or shrink. By the final stage of AD, the damage is widespread and brain tissue has shrunk significantly.
Who is at Risk of Alzheimer's Disease?
1. The primary risk factors for Alzheimer's are age, family history, and genetics:
However, there are other risk factors that you can influence. Maintaining a healthy heart and avoiding high blood pressure, heart disease, stroke, diabetes, and high cholesterol can decrease the risk of Alzheimer's. Watch your weight, avoid tobacco and excess alcohol, stay socially connected, and exercise both your body and mind.
2. Early-onset Alzheimer's affects patients under the age of 65:
This relatively rare condition is seen more often in patients whose parents or grandparents developed Alzheimer's disease at a young age, and is generally associated with three specific gene mutations (the APP gene found on chromosome 21, the PSI gene on chromosome 12, and the PS2 gene on chromosome 1).
Alzheimer's Disease: Causes:
Scientists don't yet fully understand what causes Alzheimer's disease in most people. In people with early-onset Alzheimer's, a genetic mutation is usually the cause.
Late-onset Alzheimer's arises from a complex series of brain changes that occur over decades. The causes probably include some combination of genetic, environmental, and lifestyle factors. The importance of any one of these factors in increasing or decreasing the risk of developing Alzheimer's may differ from person to person.
- Age-related changes in the brain.
- Health, environmental, and lifestyle factors.
1. Age-related changes in the brain:
One of the great mysteries of Alzheimer's disease is why it largely strikes older adults. Research on normal brain aging is shedding light on this question.
Scientists are learning how age-related changes in the brain may harm neurons and contribute to Alzheimer's damage. These age-related changes include atrophy (shrinking) of certain parts of the brain, inflammation, production of unstable molecules called free radicals, and mitochondrial dysfunction (a breakdown of energy production within a cell).
Most people with Alzheimer's disease have the late-onset form of the disease, in which symptoms become apparent in their mid-60s. The apolipoprotein E (APOE) gene is involved in late-onset Alzheimer's. This gene has several forms. One of them, APOE e4, increases a person's risk of developing the disease and is also associated with an earlier age of disease onset.
However, carrying the APOE e4 form of the gene does not mean that a person will definitely develop Alzheimer's disease, and people with no APOE e4 may also develop the disease.
Also, scientists have identified a number of regions of interest in the genome (an organism's complete set of DNA) that may increase a person's risk for late-onset Alzheimer's to varying degrees.
Early-onset Alzheimer's disease occurs in people age 30 to 60 and represents less than 5 percent of all people with Alzheimer's. Most cases are caused by an inherited change in one of three genes, resulting in a type known as early-onset familial Alzheimer's disease, or FAD.
For others, the disease appears to develop without any specific, known cause, much as it does for people with the late-onset disease.
What Else Can Alzheimer's Symptoms?
Significant cognitive and memory loss are not symptoms of normal aging. However, these symptoms do not always indicate Alzheimer's disease. Other conditions can also cause mental decline.
Symptoms that mimic early Alzheimer's disease may result from:
1. Central nervous system and other degenerative disorders:
including head injuries, brain tumors, stroke, epilepsy, Picks Disease, Parkinson's disease, Huntington's disease.
2. Metabolic ailments:
such as hypothyroidism, hypoglycemia, malnutrition, vitamin deficiencies, dehydration, kidney or liver failure.
3. Substance-induced conditions:
such as drug interactions, medication side-effects, alcohol, and drug abuse.
4. Psychological factors:
such as dementia syndrome, depression, emotional trauma, chronic stress, psychosis, chronic sleep deprivation, delirium.
such as meningitis, encephalitis, and syphilis.
Diagnosis of Alzheimer's Disease:
Doctors use several methods and tools to help determine whether a person who is having memory problems has possible Alzheimer's dementia (dementia may be due to another cause) or probable Alzheimer's dementia (no other cause for dementia can be found).
To diagnose Alzheimer's, doctors may:
- Ask the person and a family member or friend questions about overall health, past medical problems, ability to carry out daily activities, and changes in behavior and personality.
- Conduct tests of memory, problem-solving, attention, counting, and language.
- Carry out standard medical tests, such as blood and urine tests, to identify other possible causes of the problem.
- Perform brain scans, such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET), to rule out other possible causes for symptoms.
These tests may be repeated to give doctors information about how the person's memory and other cognitive functions are changing over time.
Alzheimer's disease can be definitely diagnosed only after death, by linking clinical measures with an examination of brain tissue in an autopsy.
People with memory and thinking concerns should talk to their doctor to find out whether their symptoms are due to Alzheimer's or another cause, such as stroke, tumor, Parkinson's disease, sleep disturbances, side effects of medication,
an infection, or a non-Alzheimer's dementia. Some of these conditions may be treatable and possibly reversible.
Treatment of Alzheimer's Disease:
Alzheimer's disease is complex, and it is unlikely that any one drug or other intervention can successfully treat it. Current approaches focus on helping people maintain mental function, manage behavioral symptoms, and slow or delay the symptoms of a disease.
Researchers hope to develop therapies targeting specific genetic, molecular, and cellular mechanisms so that the actual underlying cause of the disease can be stopped or prevented.
Maintaining Mental Function:
Several medications are approved by the U.S. Food and Drug Administration to treat symptoms of Alzheimer's. Donepezil (AriceptÆ), rivastigmine (ExelonÆ), and galantamine (RazadyneÆ) are used to treat mild to moderate Alzheimerís (donepezil can be used for severe Alzheimerís as well). Memantine (NamendaÆ) is used to treat moderate to severe Alzheimerís.
These drugs work by regulating neurotransmitters, the chemicals that transmit messages between neurons. They may help maintain thinking, memory, and communication skills, and help with certain behavioral problems. However, these drugs don't change the underlying disease process. They are effective for some but not all people, and may help only for a limited time.
Common behavioral symptoms of Alzheimer's include sleeplessness, wandering, agitation, anxiety, and aggression. Scientists are learning why these symptoms occur and are studying new treatments drug and non-drug to manage them.
Research has shown that treating behavioral symptoms can make people with Alzheimer's more comfortable and makes things easier for caregivers.
Stages of Alzheimer's Disease:
The three-stage Alzheimer's disease model:
- Mild/Early (lasts 2-4 yrs), Frequent recent memory loss, particularly of recent conversations and events.
- Repeated questions, some problems expressing and understanding language.
- Mild coordination problems: writing and using objects becomes difficult.
- Depression and apathy can occur, accompanied by mood swings.
- Need reminders for daily activities, and may have difficulty driving.
- Moderate/Middle (lasts 2-10 yrs) ñ Can no longer cover up problems.
- Pervasive and persistent memory loss, including forgetfulness about personal history and inability to recognize friends and family.
- Rambling speech, unusual reasoning, and confusion about current events, time, and place.
- More likely to become lost in familiar settings, experience sleep disturbances, and changes in mood and behavior, which can be aggravated by stress and change.
- May experience delusions, aggression, and uninhibited behavior.
- Mobility and coordination is affected by slowness, rigidity, and tremors.
- Need structure, reminders, and assistance with the activities of daily living.
- Severe/Late (lasts 1-3+ yrs), Confused about past and present.
- Loss of ability to remember, communicate, or process information.
- Generally incapacitated with severe to total loss of verbal skills.
- Unable to care for self. Falls possible and immobility likely.
- Problems with swallowing, incontinence, and illness.
- Extreme problems with mood, behavior, hallucinations, and delirium. In this stage, the person will need round the clock intensive support and care.
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